In electronic pianos, electronic tones (sounds) are audibly generated or sounded through an electromagnetic speaker. In some of the electronic pianos too, a sound board is provided to generate not only electronic tones but also natural spreading of tones and rich low-pitched tones. Patent Literature 1 discloses a technique in accordance with which an electromagnetic speaker is mounted on the sound board to vibrate the sound board with the electromagnetic speaker so that a tone is radiated from the sound board.